686 GREENE. [Vol. XV. 



not a strong one, only strong enough to enable one to quite 

 easily distinguish the apparatus used in the experiment. 



An important fact brought out by the above experiment is 

 that an electrical stimulation strong enough to most violently 

 stimulate the nervous system, as shown by the violent con- 

 tractions of the muscular system, may still be too weak to 

 produce phosphorescence. This fact gives a physiological 

 confirmation of the morphological result stated above that no 

 specific nerves are distributed to the phosphorescent organs. 



I can explain the action of the electrical current in these 

 experiments only on the supposition that it produces its effect 

 by direct action on the gland. 



The experiments just related were all tried on specimens of 

 the fish taken from under the rocks where they were guarding 

 the young brood. Two specimens, however, taken by hooks 

 from the deeper water of Monterey bay, could not be made to 

 show phosphorescence either by electrical stimulation or by 

 treatment with ammonia. These specimens did not have the 

 high development of the system of mucous cells of the skin 

 exhibited by the nesting fish. My observations were, how- 

 ever, not numerous enough to more than suggest the pos- 

 sibility of a seasonal high development of the phosphorescent 

 organs. 



Two of the most important parts of the organ have to do 

 with the physical manipulation of light — the reflector and the 

 lens, respectively. The property of the reflector needs no 

 discussion other than to call attention to its enormous develop- 

 ment. The lens cells are composed of a highly refractive 

 substance, and the part as a whole gives every evidence of 

 light refraction and condensation. The form of the lens gives 

 a theoretical condensation of light at a very short focus. That 

 such is in reality the case, I have proved conclusively by exami- 

 nation of fresh material. If the fresh fish be exposed to direct 

 sunlight, there is a reflected spot of intense light from each 

 phosphorescent organ. This spot is constant in position with 

 reference to the sun in whatever position the fish be turned 

 and is lost if the lens be dissected away and only the reflector 

 left. With needles and a simple microscope it is comparatively 



